1. Field of the invention
The invention relates to a signal generating device and method, and more particularly, to a single-ended oscillation device for generating a fully differential signal and method thereof.
2. Description of the Related Art
FIG. 1 is a schematic diagram of a conventional single-ended ring oscillator. A conventional single-ended ring oscillator 100 must include an odd number of inverting delay units, but cannot generate fully differential signals. In order to solve this problem, signals generated by two adjacent inverting delay units are differential-amplified to obtain full swing output signals. However, since the signals generated by the two adjacent inverting delay units are not fully differential signals (their phase difference is 180 degrees and there is a time delay of an inverting delay unit), the above approach can't generate fully swing differential output signals with a duty cycle of about 50%.
As shown in FIG. 2, when a differential ring oscillator 200 is used, the fully differential signals can be provided and amplified to obtain the fully swing differential output signals with a duty cycle of about 50%. However, with the same oscillation frequency, the power consumption of the differential ring oscillator is greater than that of the single-ended oscillator; besides, the circuit design of the differential ring oscillator is more complicated than that of the single-ended oscillator.